Prepare macaroni and cheese according to package directions, gradually stir in eggs.

Spread onto a greased 12 in pizza pan.Bake at 375 for 10 minutes. Meanwhile in a large skillet, cook beef and onion over medium heat until meat is no longer pink, drain. Stir in pizza sauce.

Spread meat mixture over macaroni crust. Sprinkle with the mushrooms, pepperoni and cheese. Bale for 10-15 minutes or until a thermometer inserted in the crust reads 160 degrees and the cheese is melted.